A clamping device of this type is known from DE 10 2004 026 438 B4. This clamping device comprises a tension rod slidably mounted within a machine spindle and a clamping set mounted within the machine spindle, which clamping set can be moved between a clamped position and a released position by means of the tension rod. In addition, a tension spring in the form of a plate spring assembly is mounted in the machine spindle for generating the clamping force of the clamping set. The tension spring is clamped between the tension rod at a rearward end, which has an enlarged diameter, and a retaining ring axially braced within the machine spindle. By means of a release mechanism disposed at the rearward end of the machine spindle, the clamping set can be moved into the released position against the force of the tension spring by means of the tension rod. Since the tension spring in this prior-art clamping device is braced on one side against the machine spindle, the machine spindle is actuated with a relatively high axial force. As a result, e.g., the bearing of the machine spindle, which is generally rotatably mounted in a spindle jacket or a spindle holding fixture, is subjected to significant wear.
Thus, there exists a need for an improved clamping device and a machine unit comprising such a clamping device.